Tuesday, November 2, 2010

Remember to water your bamboo!

I learned an important lesson today: It’s crucial to continue watering potted plants even after several rain showers—especially if daytime highs are in the mid to high 70s.

We received what I thought was a good soaking toward the end of last week, and the ground is still moist enough that supplemental watering is not necessary. However, it’s a different story for plants in containers. I happened to look at our emerald bamboo (Bambusa textilis ‘Mutabilis’) this morning and was shocked to see most leaves rolled up tightly. That’s what most bamboos do when they’re getting too dry. The rolled up leaves exhibit a smaller surface area which helps to prevent additional moisture loss.

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Rolled up leaves on developing branches of a new culm
on emerald bamboo
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The same branches a week ago

We’re keeping this particular bamboo in a 15-gallon nursery container while we’re trying to decide where to plant it. I suspect it’s fairly root-bound, which means that a good portion of the container is filled with roots, not soil, so water runs right through the container instead of being absorbed by the soil. Prior to last week’s rain, I had religiously watered the plant once day. I should not have stopped!

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See how tightly curled up these leaves are!

When I saw the signs of distress, I watered our emerald bamboo right away until water was running out the bottom of the container. I repeated this procedure an hour later. Within a couple of hours, most leaves had uncurled again.

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Leaves uncurling after watering; some remain rolled up

As I write this, about 5 hours later, the leaves on the newest (and tallest) culm are still rolled up. I will give the plant another drink later in the afternoon, and I hope that by tomorrow morning these leaves will have uncurled, too. I’m keeping my fingers crossed that my negligence caused no lasting damage.

Something similar happened a few weeks ago to a Yushania boliana, one of the largest montane bamboos. This particular plant is in a half barrel and is irrigated automatically via drip line. The amount of water it receives seems to be sufficient for normal conditions as the leaves usually look green and lush. However, a few weeks ago we had a strong wind which buffeted the culms relentlessly overnight and into the afternoon. Even though I gave the plant additional water as soon as I was able to, the tops of the new culms had already dried out past the point of return.

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Dried tops of new culms on Yushania boliana

Three quarters of the leaves recovered but about a quarter ended up drying up.

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Some Yushania boliana leaves never recovered

As ratty as the plant may look now, it’ll replace these leaves next spring. The culms whose tops dried up are still alive and should leaf out normally; they’ll just be shorter.

Since I’ve turned off our in-ground sprinklers and drip systems, I’ll have to be extra vigilant about checking our potted plants and water them as needed. Another important gardening lesson learned—for the tenth time or so.

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